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Dive into the research topics where Raissa F. P. Mendes is active.

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Featured researches published by Raissa F. P. Mendes.


Physical Review D | 2015

Possibility of setting a new constraint to scalar-tensor theories

Raissa F. P. Mendes

Scalar-tensor theories (STTs) are a widely studied alternative to general relativity (GR) in which gravity is endowed with an additional scalar degree of freedom. Although severely constrained by solar system and pulsar timing experiments, there remains a large set of STTs which are consistent with all present day observations. In this paper, we investigate the possibility of probing a yet unconstrained region of the parameter space of STTs based on the fact that stability properties of highly compact neutron stars in these theories may radically differ from those in GR.


Physical Review D | 2014

Instability of nonminimally coupled scalar fields in the spacetime of slowly rotating compact objects

Raissa F. P. Mendes; George E. A. Matsas; Daniel A. T. Vanzella

containing unstable modes in a background which is flat in the asymptotic past and stationary and axially symmetric in the future. In Sec. III we present a simple general argument that shows that the parameter space which characterizes the instability is not modified at first order in the compact object’s angular momentum. Then, we investigate secondorder deviations from staticity in a particular model, taking as the source of the gravitational field a class of slowly spinning shells. The general properties of the shell spacetime are presented in Sec. IV. Considering spinning thin shells allows us to push the analytical treatment further and arrive at clear conclusions about the role played by rotation on the instability. This is pursued in Sec. V. Section VI is devoted to a discussion of the results and to our final remarks. We assume metric signature ð− þ þþÞ and natural units in which c ¼ G ¼ ℏ ¼ 1 unless stated otherwise.


Physical Review D | 2016

Highly compact neutron stars in scalar-tensor theories of gravity: Spontaneous scalarization versus gravitational collapse

Raissa F. P. Mendes; Néstor Ortiz

Scalar-tensor theories of gravity are extensions of General Relativity (GR) including an extra, nonminimally coupled scalar degree of freedom. A wide class of these theories, albeit indistinguishable from GR in the weak field regime, predicts a radically different phenomenology for neutron stars, due to a nonperturbative, strong-field effect referred to as spontaneous scalarization. This effect is known to occur in theories where the effective linear coupling


Physical Review D | 2013

Awaking the vacuum with spheroidal shells

William C. C. Lima; Raissa F. P. Mendes; George E. A. Matsas; Daniel A. T. Vanzella

\beta_0


Classical and Quantum Gravity | 2017

Tidal deformability of boson stars and dark matter clumps

Raissa F. P. Mendes; Huan Yang

between the scalar and matter fields is sufficiently negative, i.e.


Physical Review D | 2016

Instability of nonminimally coupled scalar fields in the spacetime of thin charged shells

Jessica Santiago; Andre G. S. Landulfo; William C. C. Lima; George E. A. Matsas; Raissa F. P. Mendes; Daniel A. T. Vanzella

\beta_0 \lesssim -4.35


Classical and Quantum Gravity | 2016

Self-force and fluid resonances

Soichiro Isoyama; Raissa F. P. Mendes; Eric Poisson

, and has been strongly constrained by pulsar timing observations. In the test-field approximation, spontaneous scalarization manifests itself as a tachyonic-like instability. Recently, it was argued that, in theories where


Physical Review D | 2011

Radiation interference from sources rotating around Schwarzschild black holes

Raissa F. P. Mendes; George E. A. Matsas

\beta_0>0


arXiv: General Relativity and Quantum Cosmology | 2013

Reply to "Comment on `Quantum versus classical instability of scalar fields in curved backgrounds'"

George E. A. Matsas; Raissa F. P. Mendes; Daniel A. T. Vanzella

, a similar instability would be triggered by sufficiently compact neutron stars obeying realistic equations of state. In this work we investigate the endstate of this instability for some representative coupling functions with


Physical Review Letters | 2018

New Class of Quasinormal Modes of Neutron Stars in Scalar-Tensor Gravity

Raissa F. P. Mendes; Néstor Ortiz

\beta_0>0

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George E. A. Matsas

Spanish National Research Council

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Huan Yang

Perimeter Institute for Theoretical Physics

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Néstor Ortiz

Perimeter Institute for Theoretical Physics

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Jessica Santiago

Universidade Federal do ABC

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